The present disclosure concerns apparatus and methods for improving the function of biological passages. The ability of biological passages to expand and contract actively or passively to regulate the flow of solids, liquids, gases, or combinations thereof, may be compromised by defects or disease. One example of a condition associated with decreased functionality of a body passage is Gastro Esophageal Reflux Disease (hereinafter, “GERD”), which affects the esophagus. Other body passages that may be subject to dysfunction, defect, and disease include, but are not limited to, a fallopian tube, a urethra (for example, in the case of incontinence), and a blood vessel (for example, in the case of an aneurysm). GERD and esophageal dysfunction will be further described herein for the sake of illustration.
The normal healthy esophagus is a muscular tube that carries food from the mouth through the chest cavity and into the upper part of the stomach. A small-valved opening in the distal esophagus, called the lower esophageal sphincter (hereinafter, “LES”), regulates the passage of food into the stomach. When functioning properly, the LES muscle presents a barrier to the reflux of acid or food back into the esophagus. The LES also regulates the stomach intra-gastric pressures, regulating acidic gases from refluxing from the stomach back into the esophagus. The LES, when functioning properly, will open to allow gases to be vented from the stomach. A healthy LES at rest can resist pressure from stomach gases that are at least 10 mm Hg greater than the normal intragastric pressure. This pressure difference can regulate the amount of acidic fluid that refluxes from the stomach into the esophagus. The LES is controlled largely by two components. The primary component is intrinsic smooth muscle of the distal esophagus wall. The second component is the skeletal muscle of the crural diaphragm or esophageal hiatus. The diaphragm is a muscle separating the stomach from the chest. Studies have shown that the diaphragm may act as a sphincter around the lower end of the esophagus. The esophageal hiatus is the opening in the diaphragm where the esophagus attaches to the stomach.
If the LES relaxes, atrophies, or degrades for any reason, the contents of the stomach, which may be acidic, are allowed back into the esophagus resulting in reflux symptoms. The major mechanism for esophageal reflux, which may be associated with GERD, is the relaxation of one or both of the LES or hiatal diaphragm sphincter mechanisms. Normally occurring mechanisms that diminish or prevent GERD include peristaltic squeezing by the esophageal body, gravity (when a person is in an upright position), and neutralization by saliva.
Chronic or excessive acid reflux exposure may cause esophageal damage. Drugs may be required to manage symptoms of the damage and medical intervention, including surgical or endoscopic procedures, may be required to repair the damage.
The lining of the esophagus is called mucosa. Chronic exposure to stomach gases may cause the mucosa to become inflamed or ulcerated. Inflamed or ulcerated mucosa may lead to problems that may require medical intervention.
Barrett's Esophagus is a disease of the esophagus that may compromise esophageal function. This disease may occur when the tissue that ordinarily lines the esophagus migrates away from the lower part of the esophagus to avoid exposure to the acidic fluids against the sensitive mucosa. Barrett's Esophagus is often a precursor to esophageal cancer.
The most common symptom of GERD is dyspepsia (commonly known as “heartburn”). Dyspepsia may be defined as an acute burning sensation in the chest area typically, behind the sternum. Other symptoms of GERD may include hemorrhage, pulmonary disorders, chronic cough, intermittent wheezing, ulcers, Barrett's Esophagus, and esophageal cancer.
A conventional treatment for GERD is surgical suturing of a pleat of tissue between the LES and stomach to make the lower esophagus tighter. Suturing may be performed endoscopically using a suturing device on the end of an endoscope inserted into the esophagus through the mouth. Endoscopic procedures are less invasive than open surgery, but still require surgical incisions and great skill.
Surgery, whether endoscopic or open may provide a basic mechanical correction. Surgical procedures may relocate and affix existing tissue of the stomach, esophagus, or both to add support and structure to the LES. LES strength is increased by the added support, thus reducing the incidence of reflux.
Another conventional treatment for GERD includes the use of pharmaceutical drugs. The drugs may include acid blockers that may reduce the production of acid by the stomach. The drugs may be effective to reduce the symptoms of mild GERD, but they do not treat LES dysfunction. In general, the drugs must be administered indefinitely to maintain their efficacy.
Hiatal hernias are often associated with GERD. A hiatal hernia is an anatomical abnormality in which part of the stomach protrudes through the diaphragm and up into the chest. This occurs when the diaphragm weakens and the inner lining of the abdomen pushes through the weakened area, forming a sac or hernia. If the esophageal hernia becomes enlarged (herniated), the LES function may be compromised and the risk of GERD increased.
The treatment methods described above only treat GERD, not hiatal hernias. One conventional surgical procedure for treating both GERD and hiatal hernias is fundoplication. In this procedure, the herniated portion of the stomach is pulled back into the stomach and the upper part of the stomach is wrapped around the lower part of the esophagus. This highly invasive procedure is often initially successful, but has a high risk of morbidity (including, e.g., infection and bleeding).
It is therefore an object of the present invention to develop treatments for GERD and hiatal hernias which are less invasive than fundoplication, yet are based on the principles of fundoplication.